Adaptation of the Vestibulo-Ocular System to Rotation1

2015 ◽  
pp. 120-127 ◽  
Author(s):  
R. Malcolm
Keyword(s):  
Ocular System

Inactivation of Semicircular Canals Causes Adaptive Increases in Otolith-Driven Tilt Responses

2002 ◽  
Vol 87 (3) ◽  
pp. 1635-1640 ◽  
Author(s):  
Dora E. Angelaki ◽  
Shawn D. Newlands ◽  
J. David Dickman
Keyword(s):  
Eye Movements ◽  
Semicircular Canal ◽  
Translational Motion ◽  
Semicircular Canals ◽  
Vertical Axis ◽  
Lateral Motion ◽  
Functional Interaction ◽  
Gaze Stabilization ◽  
Theoretical Evidence ◽  
Ocular System

Growing experimental and theoretical evidence suggests a functional synergy in the processing of otolith and semicircular canal signals for the generation of the vestibulo-ocular reflexes (VORs). In this study we have further tested this functional interaction by quantifying the adaptive changes in the otolith-ocular system during both rotational and translational movements after surgical inactivation of the semicircular canals. For 0.1–0.5 Hz (stimuli for which there is no recovery of responses from the plugged canals), pitch and roll VOR gains recovered during earth-horizontal (but not earth-vertical) axis rotations. Corresponding changes were also observed in eye movements elicited by translational motion (0.1–5 Hz). Specifically, torsional eye movements increased during lateral motion, whereas vertical eye movements increased during fore-aft motion. The findings indicate that otolith signals can be adapted according to a compromised strategy that leads to improved gaze stabilization during motion. Because canal-plugged animals permanently lose the ability to discriminate gravitoinertial accelerations, adapted animals can use the presence of gravity through otolith-driven tilt responses to assist gaze stabilization during earth-horizontal axis rotations.

Development of embryonic rat eyes in organ culture

Development ◽  
1968 ◽  
Vol 19 (3) ◽  
pp. 407-414
Author(s):  
R. Christy Armstrong ◽  
Joel J. Elias
Keyword(s):  
Organ Culture ◽  
Culture Medium ◽  
Folic Acid Deficiency ◽  
Experimental Conditions ◽  
Acid Deficiency ◽  
Series Of Experiments ◽  
Development In Vitro ◽  
Ocular System

Abnormalities of the ocular system which appear in organ culture in Waymouth's medium with freshly added glutamine (Armstrong & Elias, 1968) resemble those caused by transitory pteryolglutamic acid (PGA or folic acid) deficiency in vivo (Armstrong & Monie, 1966). The configurations of such malformations as lens herniations, retinal diverticula, and rosette-like formations of the retina are remarkably similar in both cases. The experiments reported in this paper were undertaken in an effort to understand the mechanisms involved in the production of similar abnormalities by two very different experimental conditions: the addition of glutamine in vitro and the transitory deficiency of PGA in vivo. One series of experiments involved the effects of manipulation of the PGA and glutamine content of the culture medium on eye development in vitro. Parallel studies on PGA-deficiency in vivo were undertaken in conjunction with organ-culture experiments in order to compare the effects on abnormal eye morphogenesis.

scholarly journals A NOVEL TWO-STEP STRATEGY FOR POINT CORRESPONDENCE IN MULTI-OCULAR SYSTEM

2013 ◽  
Vol 6 (1) ◽  
pp. 136-153 ◽  
Author(s):  
Haibin Wang ◽  
Qing He ◽  
Guan Guan ◽  
Bin Leng ◽  
Dewen Zeng
Keyword(s):  
Point Correspondence ◽  
Ocular System

Measuring circadian lighting through high dynamic range photography

2018 ◽  
Vol 51 (5) ◽  
pp. 742-763 ◽  
Author(s):  
B Jung ◽  
M Inanici
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Built Environments ◽  
Natural Environments ◽  
Design Decisions ◽  
High Dynamic ◽  
Ocular System ◽  
The Impact ◽  
Strong Linear Relationship ◽  
Internal Body

The human ocular system functions in a dual manner. While the most well-known function is to facilitate vision, a growing body of research demonstrates its role in resetting the internal body clock to synchronize with the 24-hour daily cycle. Most research on circadian rhythms is performed in controlled laboratory environments. Little is known about the variability of circadian light within the built and natural environments. Currently, very few specialized devices measure the circadian light, and they are not accessible to many researchers and practitioners. In this paper, tristimulus colour calibration procedures for high dynamic range photography are developed to measure circadian lighting. Camera colour accuracy is evaluated through CIE trichromatic (XYZ) measurements; and the results demonstrate a strong linear relationship between the camera recordings and a scientific-grade colorimeter. Therefore, it is possible to correct for the colour aberrations and use high dynamic range photographs to measure both photopic and circadian lighting values. Spectrophotometric measurements are collected to validate the methodology. Results demonstrate that measurements from high dynamic range photographs can correspond to the physical quantity of circadian luminance with reasonable precision and repeatability. Circadian data collected in built environments can be utilized to study the impact of design decisions on human circadian entrainment and to create guidelines and metrics for designing circadian friendly environments.

Mouse Pitx2 deficiency leads to anomalies of the ventral body wall, heart, extra- and periocular mesoderm and right pulmonary isomerism

Development ◽  
1999 ◽  
Vol 126 (24) ◽  
pp. 5749-5758 ◽  
Author(s):  
K. Kitamura ◽  
H. Miura ◽  
S. Miyagawa-Tomita ◽  
M. Yanazawa ◽  
Y. Katoh-Fukui ◽  
...  
Keyword(s):  
Body Wall ◽  
Genomic Structure ◽  
Homeobox Gene ◽  
Lacz Gene ◽  
Mitral Valves ◽  
Lateral Body ◽  
Asymmetrical Pattern ◽  
Ocular System ◽  
Deficient Mice ◽  
Pitx2 Expression

Pitx2, a bicoid-related homeobox gene, is involved in Rieger's syndrome and the left-right (L-R) asymmetrical pattern formation in body plan. In order to define the genomic structure and roles of Pitx2, we analyzed the genomic structure and generated Pitx2-deficient mice with the lacZ gene in the homeobox-containing exon of Pitx2. We were able to show that among three isoforms of Pitx2, Pitx2c shows asymmetrical expression whereas Pitx2a, Pitx2b and Pitx2c show symmetrical expression. In Pitx2(−)(/)(−) embryos there was an increase in mesodermal cells in the distal end of the left lateral body wall and an amnion continuous with the lateral body wall thickened in its mesodermal layer. These changes resulted in a failure of ventral body wall closure. In lung and heart in which Pitx2 is expressed asymmetrically, right pulmonary isomerism, atrioventricular canals with prominent swelling, and juxtaposition of the atrium were detected. The hearts failed to develop tricuspid and mitral valves and a common atrioventricular valve forms. Further, dysgenesis of the Pitx2(−)(/)(−) extraocular muscle and thickening of the mesothelial layer of cornea were observed in the ocular system where Pitx2 is expressed symmetrically, and these resulted in enophthalmos. The present study shows that Pitx2 expressed in various sites participates in morphogenesis through three types of actions: the involvement of asymmetric Pitx2 expression in the entire morphogenetic process of L-R asymmetric organs; the involvement of asymmetric Pitx2 expression in the regional morphogenesis of asymmetric organs; and finally the involvement of symmetric Pitx2 expression in the regional morphogenesis of symmetric organs.

scholarly journals Polysaccharide-Based Nanomaterials for Ocular Drug Delivery: A Perspective

2020 ◽  
Vol 8 ◽  
Author(s):  
Haozhe Yu ◽  
Wenyu Wu ◽  
Xiang Lin ◽  
Yun Feng
Keyword(s):  
Drug Delivery ◽  
Structural Instability ◽  
Ocular Drug Delivery ◽  
Synthesis Process ◽  
Ocular Tissues ◽  
Drug Solubilization ◽  
Physiological Structure ◽  
Ocular System ◽  
Novel Drug ◽  
Drug Nanocarriers

Ocular drug delivery is one of the most challenging issues in ophthalmology because of the complex physiological structure of the eye. Polysaccharide-based nanomaterials have been extensively investigated in recent years as ideal carriers for enhancing the bioavailability of drugs in the ocular system because of their biocompatibility and drug solubilization. From this perspective, we discuss the structural instability of polysaccharides and its impact on the synthesis process; examine the potential for developing bioactive polysaccharide-based ocular drug nanocarriers; propose four strategies for designing novel drug delivery nanomaterials; and suggest reviewing the behavior of nanomaterials in ocular tissues.

scholarly journals Topical Application of Liriope platyphylla Extract Attenuates Dry Eye Syndrome Induced by Particulate Matter

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Su Jeong Song ◽  
Soo-Wang Hyun ◽  
Tae Gu Lee ◽  
Bongkyun Park ◽  
Kyuhyung Jo ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Dry Eye ◽  
Topical Administration ◽  
Air Pollutant ◽  
Dry Eye Syndrome ◽  
Protective Effects ◽  
Corneal Epithelial ◽  
Liriope Platyphylla ◽  
Ocular System

Particulate matter (PM) is a type of air pollutant that poses a risk to human health. In the ocular system, PM causes or aggravates dry eye syndrome (DES) by damaging the corneal and conjunctival epithelia. Liriope platyphylla has been used traditionally as an expectorant, antitussive agent, and tonic in Korea. However, the effects of Liriope platyphylla extract (LPE) on PM-induced ocular damage have not been elucidated. In this study, we evaluated the in vivo protective effect of LPE against PM-induced DES in rats. Topical administration of LPE attenuated the PM-induced decrease in tear volume and reduced corneal epithelial irregularity and damage. LPE also protected against PM-induced disruption of the corneal mucin-4 layer and reduction in the conjunctival goblet cell density. These findings suggest that LPE has protective effects against PM-induced DES.

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